72709531 has 2 divisors, whose sum is σ = 72709532. Its totient is φ = 72709530.

The previous prime is 72709519. The next prime is 72709541. The reversal of 72709531 is 13590727.

It is a strong prime.

It is an emirp because it is prime and its reverse (13590727) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72709531 - 2⁹ = 72709019 is a prime.

It is a super-2 number, since 2×72709531² = 10573351796479922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (72709541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36354765 + 36354766.

It is an arithmetic number, because the mean of its divisors is an integer number (36354766).

Almost surely, 2^72709531 is an apocalyptic number.

72709531 is a deficient number, since it is larger than the sum of its proper divisors (1).

72709531 is an equidigital number, since it uses as much as digits as its factorization.

72709531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13230, while the sum is 34.

The square root of 72709531 is about 8526.9883898127. The cubic root of 72709531 is about 417.3788592802.

The spelling of 72709531 in words is "seventy-two million, seven hundred nine thousand, five hundred thirty-one".